Magnetic sensors are devices adapted to sensing magnetic fields and transforming variations thereof into electrical signals, and thereby outputting the electrical signals. Magnetic sensors have different types, including giant magneto resistive (GMR) sensors, anisotropic magneto resistive (AMR) sensors, and the like. Taking an AMR sensor for example, it may include a layer of NiFe alloy which serves as a magnetic resistive layer. When an external magnetic field is applied to the magnetic resistive layer, it can cause magnetic domains of the magnetic resistive layer to rotate, thus resistance of the magnetic resistive layer may vary. Variations of the resistance of the magnetic resistive layer can be indicated via variations of output voltages. Accordingly, the external magnetic field is able to be detected.
In recent years, after homotaxial magnetic sensors and biaxial magnetic sensors, anisotropic magneto resistive sensors have come into an era of triaxial (3D) magnetic sensors. In practice, the 3D magnetic sensors are able to detect magnetic signals from three directions (specifically, direction X, direction Y and direction Z) in a detection space. Thus, the 3D magnetic sensors have been widely used.
Nowadays, integrated circuit technologies are applied to the field of magnetic sensor, which accelerates large scale productions of magnetic sensors. Referring FIG. 1 to FIG. 3, an existed process for forming a 3D magnetic sensor is illustrated.
As shown in FIG. 1, the forming process includes: providing a semiconductor substrate 10; forming an insulating layer 11 on the semiconductor substrate 10; forming a groove in the insulating layer 11; forming a diffusion barrier layer 12 on sidewalls and a bottom surface of the groove 11 and a top surface of the insulating layer 11; forming a magnetic film 13 on the diffusion barrier layer 12; and forming a tantalum nitride film 14 on the magnetic film 13.
As shown in FIG. 2, the forming process further includes: forming a photoresist film on the tantalum nitride film 14; and implementing an exposure process to the photoresist film for forming a patterned photoresist layer 15.
As shown in FIG. 3, the forming process further includes: etching the tantalum nitride film 14 by taking the patterned photoresist layer 15 as a mask until the magnetic film 13 is exposed, so as to form a tantalum nitride layer 16; removing the patterned photoresist layer 15; and etching the magnetic film 13 by taking the tantalum nitride layer 16 as a mask, so as to form a magnetic resistive layer 17.
However, it may have some difficulties for precisely controlling dimensions of 3D magnetic sensors by using the existing method.